Pope Francis has paid tribute to those who suffered and died in Lithuania during Soviet and Nazi occupations on the second day of his visit to the Baltic state.

During Mass in a park in Lithuania's second city, Kaunas, Francis on September 23 honored Jews who were executed or sent off to extermination camps during the three-year Nazi occupation and the Lithuanians who were deported to gulags or were oppressed at home during five decades of Soviet occupation.

'Earlier generations still bear the scars of the period of the occupation, anguish at those who were deported, uncertainty about those who never returned, shame for those who were informers and traitors,' Francis told a crowd of about 100,000 people.

Pope Francis also said that society should be vigilant of 'any whiff' of resurgent anti-Semitism, calling for new generations to be taught the horrors of the Holocaust.

Later in the day, Francis was set to visit the World War II Jewish ghetto in Vilnius and the capital's Museum of Occupations and Freedom Fights, which is housed in a former KGB building and dedicated to the crimes of the Soviet regime.

On September 22 in Vilnius, the pope warned against political forces that would seek to eliminate other cultures, and called on Lithuania to use its decades of occupation by the Soviets and the Nazis as a basis for battling intolerance in the world.

Lithuania is the pontiff's first stop on his regional tour that will also bring him to Latvia and Estonia, as the three countries mark their 100th anniversary of independence this year.

Lithuania, Latvia, and Estonia were part of the Russian Empire and briefly Soviet Russia before they declared independence 100 years ago.

The small countries were occupied by the Soviet Union in 1940 and by Germany between 1941 and 1944 during World War II.

They regained independence from the Soviet Union in August 1991 and joined the European Union and NATO in 2004.

According to the Vatican, around 80 percent of the Lithuanian population is Catholic. Latvia is a primarily Lutheran country, while Estonia is largely nonreligious and has a small Catholic population of around 5,000.

John Paul II in 1993 was the only other pope to visit the three Baltic states.